Dolomitic articles and method of making same



mama Kai. 31, 1926.

Examiner UNITED STATES PATENT OFFICE.

HIBAM S. LUKENS, OF PHILADELPHIA, PENNSYLVANIA, ASSIG-NOR TO SOLIIDIFIER CORPORATION, OF IHIIIADELPHIA, PENNSYLVANIA, A CORPORATION OF DELA- WARE.

nonom io An'rIcLEs AND mnrnonpr MAKING SAME. in Drawing. Application filed August 4, 1925. Serial No. 48,139. I

My invention relates to the manufacture ents mixed in the following proportions by of shaped articles from a mixture of magweight: nesium oxide and calcium carbonate, wheth- P Per cent i er such mixture is used alone or with aggre- L- gi gi ma eslte gates. The mixture of MgO and CaCO may be obtained by mixing the two in thd 20 30 mes desired proportions, or by the selective cal- Water was fldded the above mixture ll i ti f d l it t 50 m 1n the proportion of 16.3 cubic centimeters mm of water to each 100 grams of dry mixture. ;mmmfi' The whole Was thoroughly mixed and introa 3 mg 9 Se ec W v ca cme 'f t m'd duced into ordinary tensile briquette molds such as are commonly used in cement testing. on

nesite 12!! mesh s lex a In either case. I term the material so obtained lastic calcined dolomite; and on account 0 hecheapness of dolomite, I prefer to use the selectively calcined dolomite with or without varying its ingredients artificially, the term being used to include either case.

I have discovered that if the MgO in such a mixture is converted either partially or preferablv wholly into MgCO,. the presence of CaCO, greatly aids in the reaction and makes the process commercially feasible and advantageous.

This carbonation of the M content may be carried out in various ways, but is preferably accomplished by subjecting the shaped article containing MgO and (31100 mixture whether obtained by selective calcination of dolomite or by artificial mixing or by both: and whether aggregate is used or not, and while the mixture is damp or wet from the presence of waterhor water vaporntortheactiomofllfl gas. 'Ilheduran. O ihis carbonatinm finhdfipfinfliH29 ve qinateri ls ,uscd ihe amount- .Qifi present, the pressureuusedin jogging: the article. I, will. now deseribe-somespecific examples of carrying-.out.. my. procee in one of which the MgQ content is substantially entirely converted into a carbonate and the other of which it is only partially converted; a dry mixture of lastic cal ed ma crushed marble was prepare,

at atmos lien ssure t ta a em era a-vera v 9 the conclusion f 9 6 hours exposure to the action of the gas, 68 three 0 showed an average tensile pounds per square inch.

After six days exposure to the action of 70 the gas, three more briquettes were removed, heated to constant weight at C. and pulled. These showed an average tensile strength of 37 3 pounds per square inch.

After eight days exposure to the action 76 of carbon dioxide gas, three more briquettes were removed. heated to constant weight at 100 C. and pulled. These briquettes showed an average tensile strength of 408 pounds per square inch.

Examination of other briquettes indicated that after eight days exposure to the action of the gas, little or no additional carbon dioxide was absorbed by the material.

In using the astic calci d dolomite, whether natural gr artificial, 1% 1s preferafily ground to the fineness of ordinary commercial plastic calcined magnesite, in order to give a bond of maximum strength. At this degree of fineness, the CaCO, content functions in a way similar to that of the finely ground silex now used, with similarly ground MgO in making stucco, tile, floor ing, etc., and at the same time the CaCO, aids iin the carbonating of the MgO, as above state The reason for the increased carbonation of the MgO in the presence of CaCO is not known to me at present. The CaCO may exert a catalytic action upon the reac- I tion, but whatever its rationale may be, the

presence of CaCO does definitely and materially increase the speed and effectiveness of the reaction.

The material may be cast inmolds, or

spread in place or pressed in dies, and the CO treatment may be applied either before or after removal from the mold or dies when such are used. The articles thus formed are dolomitic in character, since they contain the carbonates of both calcium and magne' sium. They possess considerable structural strength, are water and fire resistant. They also possess good di-electric properties, especially when suitable aggregates are used therewith. When used for dielectric purposes, the dielectric strength may vary by .using aggregates of suitable dielectric properties. By varying such a re s and their state of fineness, the dielectric properties may be varied as desired. For high resistance, aggregates of high resisting properties are used, while for permitting passage of current better conductors may be used for the aggregate.

80 The carbonating step may be carried out by a carbonated water or by passing CO through water in which the article is immersed.

Where the plastic calcined dolomite is 85 used as'a l ip der, the aggregate may be either organic or inorganic, and may be used in any desired state of subdivision. Other ways of converting the MgO content, either partially or wholly into carbonate, may be employed, and other changes may be made without departing from my invention, since consider myself the first to carbonate the into a binder while accelerating said reaction by the presence of the CaCO admixed therewith.

3. In the manufacture of composition articles, the process consisting of carbonating MgO to convert it into a binder while accelerating said reaction by the presence of CaOO in moistened admixture therewith.

4. In the manufacture of composition articles, the process consisting of making a wet mixture of selectively calcined dolomite containing MgO and (321C shaping the same, and carbonating the MgO to convert it into a bindenwhile accelerating said reaction by the presen'e of the CaCO in admixture therewith.

5. In the manufacture of composition articles, the process consisting of adding MgO to selectively calcined dolomite containing MgO and CaCO preparing a moistened mixture thereof, and then carbonating the MgO to convert it into a binder while accelerating said reaction by the presence of the CaCO admixed therewith.

- 6. As a new article of manufacture, artificial stone comprising a pulverulent aggregate other than ores of metals and containing a material proportion of calcium carbonate, said a re ate bein cemente (r 1n er, su stantially all of which conmagnesium carbonate chemically formed in place from magnesium oxide in admixture with the calcium carbonate in a wet plastic mixture of the aggregate and binder, said stone having the strength generally required in building materials.

7. As a new article of manufacture, artificial stone formed with a wet mixture of a selectively calcined dolomite containing MgO and (32100 and containing MgCO chemically formed from the MgO in place in the presence of the admixed CaCO said stone having the strength generally required in building materials.

8. As a new article of manufacture, artificial stone comprising selectively calcined dolomite containing MgO and CaCO with an added percentage of MgO in a wet admixture, the MgO being at least partially changed to MgCO in the presence of admixed CaCO said stone having the strength generally required in building materials.

In testimony whereof I have hereunto set my hand.

HIRAM S. LUICENS. 

